The present invention is related to a device for a retention of products on a transporting surface in a folder, particularly for web-fed rotary printing presses.
U.S. Pat. No. 2,031,780 is related to a rotary cutting and folding mechanism for printing machines. In this solution pins are disclosed, carried by one of the folding cylinders to temporarily hold the leading edge of the web or the sheets. According to this disclosure retractable pin elements are assigned to a cutting knife arranged on a cutting cylinder and corresponding anvil bars are assigned to a folding cylinder. Said pin elements are arranged as to penetrate an incoming web of material or a sheet to be seized on a respective transporting cylinder""s surface. A product rim being penetrated by punched holes of said pin elements is subject to further trimming operations when finishing the respective folded products and nowadays primarily is acceptable by the customer only on newspapers.
U.S. Pat. No. 1,900,288 discloses a folding cylinder to the surface of which a plurality of anvil bars is assigned. Similar to the disclosure according to U.S. Pat. No. 2,031,780 previously described, retractable pin elements are assigned to each of said anvil bars. Said anvil bars cooperate with knives received on the circumference of a cutting cylinder. Said pin elements are mounted within the interior of said folding cylinder. Similar to the disclosure according to U.S. Pat. No. 2,031,780 said retractably mounted pin elements penetrate said products to be conveyed on the surface of the respective folding cylinder.
U.S. Pat. No. 4,445,881 is related to a method and apparatus for improving newspaper folding and cutting mechanisms. The improvement is related to folding newspapers in the collecting mode. Inside and outside web sections are printed with the same number of lines and transferred to a folding cylinder which collects them in an overlapping relation. Expanding means incorporated in the body of the cylinder expand its effective radius to permit the trailing edge of the outside section to be cut to a length equal to that of the inside section without recutting the inside section again. The collected sections are then passed through second fold rollers for final folding.
U.S. Pat. No. 5,122,109 concerns a folding drum in a folding apparatus for a rotary printing press. Tips of folding blades project to the outside of the folding drum through gaps between the respective blades. At least two bands are integrally connected by a respective band mount position with a plurality of groups of such integrally connected bands being provided. Each band mount position is mounted to the folding drum via respective adjusting devices such that the expansion of the bands of each group of the folding drum can be adjusted. Preferably each adjusting device includes an adjusting plate engaged with an adjusting rack to which the bands are mounted and an adjusting shaft. The adjusting plate is mounted to the adjusting shaft at an eccentric position with respect to its engagement with the adjusting rack.
In known folders according to the state of the art, a set of cutting cylinders is included to create the signatures which are then forwarded into an accelerator section made of strips of transferring material such as tapes, to give an example.
Several methods are employed to prevent the signatures from opening after it has been severed from a web of material and forwarded into respective sets of tapes. At high speeds the forces acting on the book are too large and render most of these methods ineffective.
Other methods include cutting a portion of signature in the cutting cylinders"" area, then performing the final cut in a second pair of cutting cylinders or directly on a pinless transfer cylinder.
Accordingly, it is an object of the present invention to prevent respective leading edges of web of materials from opening up during a transitory period after the previous signature has been severed from the web of material.
A still further object of the present invention is to introduce a respective leading edge of a web of material into a set of tapes accurately, the respective sets of tapes assigned to a further cylinder of a respective folder apparatus.
According to the invention, a device for seizing flat material comprises:
a transfer cylinder rotating about an axis and having an outer surface,
a cutting cylinder cooperating with said transfer cylinder, said cutting cylinder having at least one knife mounted thereon, and
a set of product seizing elements arranged on the outer periphery of said cutting cylinder actuatable about a common center point, tips of said product seizing elements cooperating with counterparts on the surface of said transfer cylinder.
The advantages of the present invention are to be seen in that the leading edge of webs of material is under positive control upon a respective transitory period after the respective previous signature has been cut from said web of material. Thus, an opening up of the respective leading edge is prevented. An opening of the respective leading edge of the web of material would result in an inaccurate insertion or the occurrence of dog ears of the respective leading edge upon transfer of said leading edge into a respective sets of tapes after the transitory period. The accuracy of product transfer during the respective transitory period determines the accuracy of folding operations during the respective signature""s transport through the folder apparatus.
In further embodiments of the present invention said product seizing elements are arranged on the surface of a cutting cylinder and actuated when a respective new leading edge travels upon the respective circumference of a transfer cylinder. To allow for seizing the entire leading edge of the respective web of material, said product seizing elements may be arranged spaced apart from each other, extending over the entire width of the respective cutting cylinder. To allow for a relative movement of said product seizing elements said product seizing elements being shaped as finger elements are rotatably mounted in brackets. Said brackets are to be arranged in a simple and easy manner on the respective face portions of the cutting cylinder for example. To allow for simultaneous movement of the respective product seizing elements when actuated said seizing elements are arranged on a common axis.
Said common axis is journalled in respective levers which are rotatably mounted about center points to allow for a seizing movement of said product seizing elements. Said seizing movement occurs when a respective dwell sections of a cam element assigned to said cutting cylinder actuates a cam follower mounted to said lever which is mounted pivotably about the previously mentioned center point.
The seizing movement of the tips of the respective seizing elements is initialized when a previously cut signature from the leading edge of the web of material is created. Then, said tips of said product seizing elements engage said newly created leading edge positioned above a respective counterpart for a cutting operation. To allow for a supported but still flexible seizing operation, said leading edge of a web of material is positioned above an anvil bar received in respective grooves on the surface of said transfer cylinder, the anvil bars having a rather elongated shape to enlarge said leading edges seizing zone.
Said product seizing elements are preferably mounted to respective product conducting cylinders or pinless folders assigned to respective web-fed rotary printing presses for commercial and newspaper printing.